1. Field of the Invention
The present invention relates to a certification card and more particularly to an optical recording card having hologram contained therein.
In recent years cards having a variety of information recorded have been widely used as ID card, cash card, bank card or the like.
2. Background of the Prior Art
This kind of card is required to record various information such as individual's data and issuance company's data. In the eariler age such information are recorded in the form of visual characters and symbols and in the later age they are recorded in the form of electrical signals using magnetism. However, there is a need of taking counteractions against preventing an occuurance of alteration and increased amount of information.
Accordingly, in the latest years optical recording cards to which an optical recording technique is applied is developed. These optical recording cards have information recording medium each of which includes an optical reflective surface.
Such a card is called as optical recording card. Such a card is typically constructed in such a manner that a card front board and a rear board made of plastic material are adhered to one another and an optical recording layer is interposed therein. The optical recording layer is so constructed that its optical reflective surface has an optical reflective layer and the optical reflective surface is formed with various pits and the pits are detected by difference in optical reflectivity from the data pits in the presence of laser beams so that data contained therein are read.
On the other hand, utilization of hologram for cirtification card is already proposed (refer to, for instance, official gazette of Japanese Laying-Open of application No. 6782/1986 and official gazette of Japanese Laying-Open of application No. 176969/1986). Hologram is such that informations concerning amplitude and phase of light wave from an object is recorded simultaneously. When the hologram is exposed to light again, light waves having the same amplitude and phase as those of light from the original object can be reproduced and thereby three-dimensional image can be reproduced. This phenomenon can be applied to certification card whereby an appearance of the card can be improved, informations contained in the card has a highly increased density and it can be expected that falsification and alteration of the card are achieved only with great difficulties. In particular, due to the fact that a technique for producing hologram by press operation on transparent substrate has been developed, it becomes possible to carry out mass production of hologram and moreover utilization of hologram can be easily achieved.
Accordingly, since a certification card is provided with both optical recording portion and hologram portion, it is assured that an amount of informations to be contained in a card has a highly increased density and falsification and alteration of the card is achieved only with much difficulties.
However, if the optical card and hologram portion are prepared separately and they are attached to the card, the result is that the card becomes complicated in structure, the number of components and required manhours increase in a simple additive manner and therefore the card is produced at an expensive cost.